**6. Conclusions**

Technical aspects related to the integration of DER with the power systems can be treated as boundary conditions for the VPP planning and operation strategies. This article presents indicated results obtained for a specific case of a VPP and a broad generalization for another VPP location is not easy to achieve. However, the presented assessment method, the methodology of the studies and investigations, can be adapted and applied to another VPP topology. In addition, the definition of limitations on VPP resources formulated by the technical aspects can be further used as a prerequisite for economic research. For example, based on the studies carried out, it was indicated that planned battery energy storage in the investigated grid covered by the VPP could be increased from the planned capacity of 0.5 MW to 1.0 MW. Therefore, this result allowed us to investigate the impact of the size of the energy storage system to economic efficiency in associated work [36].

**Author Contributions:** Conceptualization, T.S., E.R.-S., M.W.; methodology of technical aspects, T.S., M.S., W.R.; methodology of economic aspects, E.R.-S., M.W.; software for technical simulation, M.S.,W.R., J.S.; software for economic calculation, E.R.-S.; formal analysis in content of technical aspects, T.S., M.J., R.L., J.R., D.K., P.K.; formal analysis in content of economic aspects, E.R.-S., M.W.; investigation in the range of technical aspects, T.S., W.R., M.S., M.J., B.S.; investigation in the range of economic aspects, E.R.-S., M.W.; resources of technical aspects, D.K., R.L., J.R., M.J., T.S., Z.L., P.K.; resources of economic aspects, E.R.-.S., M.W.; technical data curation, J.S., M.S., D.B., P.J.; economic data curation, E.R.-S., M.W.; visualization of technical aspects, W.R., M.J., D.K., P.K.; visualization of economic aspects E.R.-S., M.W.; writing—original draft preparation, T.S., M.J., D.K., J.R., R.L. and E.R.-S., M.W.; writing—review and editing, T.S., M.J., E.R.-S., M.W.; supervision, T.S., M.W.; project administration, T.S., P.J.; funding acquisition, T.S., P.J. All authors have read and agreed to the publisher version of the manuscript.

**Funding:** This research was funded by the National Center of Research and Development in Poland, the project "Developing a platform for aggregating generation and regulatory potential of dispersed renewable energy sources, power retention devices and selected categories of controllable load" supported by European Union Operational Programme Smart Growth 2014-2020, Priority Axis I: Supporting R&D carried out by enterprises, Measure 1.2: Sectoral R&D Programmes, POIR.01.02.00-00-0221/16, performed by TAURON Ekoenergia Ltd.

**Acknowledgments:** The research uses annual weather conditions and power production data of PV power plant provided by Center of Energy Technologies in Swidnica, Poland. ´

**Conflicts of Interest:** The authors declare no conflict of interest.
